Method of drying air for blast-furnaces.



- M. W. JOHNSONQ JB. METHOD OF DRYING AIR r011 BLAST FURNACES.

APPLICATION nun NOV. 2, 1911.

Patented Apr. 21, 1914.'

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WITNESSES: I NTOR k? MAM M. W.- JOHNSON, JR. METHOD OF DRYING AIR FOR BLAST FURNACES.

APPLICATION FILED now-2. 1911.

1,093,859. N Patented Apr. 21, 19m

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WITNESSES: ZZZ: [NVENTOR W N IL-:3 Aziomey M. W. JOHNSON, JR. METHOD OF DRYING AIR FOR BLAST FURNACES.

APPLICATION FILED NOV. 2, 1911.

1,093,859. Patented Apr. 21', 1914.

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5 7 Y I 1' z WIT/1155555; k 3,7 [NVENTOR Affamey UNITED STATES rnrnnrorricn MARK w. :ronnson, an, or mammalian, Amman.

METHOD-OF DRYIENG AIR FOR BLAST-FURNACES.

i ,ooasria Specification of Letters Patent.

Patented Apr, 21, 1914.

Application filed November 2, 1911. Serial No. 658,248.

To allwliomt'tmay concern. I I

lie it known that I, Mann W. JoHNsoN, J11, a citizen I America, residing at ,llirmingham, 1n the county of Jefferson and State of Alabama, have invented certain new and useful Improvements in ll'lethods of Drying A1r for lilast Furnaces, of which the follo'wmg 1s a specification.

My invention relates to'systems for obtaining dry blast for blast furnaces and has for its object to devise a more economical system than the simple freezing system" heretofore used for eliminating the great losses due to moisture inthe blast.

1 term my system a compression, cooling and reheating system which is based upon the. utilization of a gas, such as air, having a high resistance to liquefaction and the trealii'ient of said air so as to reduce the cost ol o wration, the quantity of apparatus and the horse power required to a minimum, thereby bringing the recognized economy of a dry blast within easy reach of the praccubic foot, and the ten'iperature is notchanged, half of the moisture will be condensed. For any other degree of humidity, the dew-point will be either lowered or passed, depending upon-the amount of compression. Any given quantity of free air, in order to have its moisture reduced to say 1.27 grains per cubic foot, would have to be cooled down to a temperature of 20. degrees 1 1, whereas, if it were first compressed to say '16 lbs. gage pressure, it wouldhave to be cooled only to 38 degrees, a. saving, in refrigerating effect of 17% degrees. The result of this is a saving in the size and horse power ot the refrigerating engine, and a sai'ing in the quantity of cooling surface in the cooling chambers, etc.

Second The temperature of the blast is kept always a few degrees above the freezof the United States of ing point, and the condensed moisture is drawn ofi' continuously in the liquid state by traps, instead of being frozen. This eliminates the necessity for duplicate cooling chambers, reducing the cost to less than one half at this point, first, because only one chamber is required instead of two, and second, because the quantity of cooling surface in a chamber is less-owing to the removal of the ice coat, which, being a poor conductor of heat, lowers the efliciency of the cooling surfaces. valves for same are eliminated.

Third: The blast is reheated after being dried,'instead of leaving the drying appara-.

tus cold. The reheating is done by conducting the cold dry blast along one slde of sur- Also, because the by-passes and faces which have the Warm Wet blast passingon the other side in the opposite direction. The effect of this is to cool the wet blast to a certain extent, and relieves the refrigerating engine to that amount, which is consider- I able, being more than half of the total. This resultsin another saving in the size and horse power of the' refrigerating engine. The heat developed by compression in the blowing engines is also removed and returned by this process.

My invention further difl'ers inzlthat the,

refrigerating engine is operated with anhydrous compressed air as the heat extract-- ing-medium, instead of anhydrous, compressed and liquefied ammonia. The cooling elfeet is accomplished by the expansion of the compressed air against a piston in one cylinder which helps todrive a piston in another cylinder in which the air is being compressed atthe same time; lnstead of having a compression cylinder only as 1s the case with the ammonia machlne.

With ammonia, the principal refrigerating effect is obtained by evaporation, the gas being first compressed, cooled and liquefied; and afterward released from pressure and evaporated. The release from pressure is usually done by passing the liquid through needle v,alves,from which it emerges under a less pressure, and also partially evapo-' rated. By this use of needle valves, the expansive force of the gas is lost so far as the production of power for driving the refrigerator is concerned, and it is this feature of the ammonia machine which calls for more power to drive itthan the compressed air machine. So far as its refrigerating effect is concerned, one gas is just as efiicient as another, but since liquefaction of the gascauses loss of power and necessitates the use i put into service; all that is necessary being what I term the waste hcater A.

to dry it and compress it.

My invention further comprises the details of construction and arrangement of parts hereinafter more particularly de scribed and claimed, reference being had to the accompanyingdrawings, in which 7 Figure 1 is a side elevation of my improved apparatus. Fig. 2 is a plan view showing the entire dry blast apparatus and a power plant for effecting the compression of the air utilized. Fig. 3 is a diagrammatic view to illustrate the circuits of the air blast to the refrigerating medium in my system. Fig. 4 shows in side elevation at gairof heat transfer cylinders. Fig. 5 is a etail'sectional view through a portion of one of said cylinders, and Fig. 6 is a partial planview enlarged of one of said: ylinders with the head removed. 1

Similar reference numerals refer to similar parts throughout the drawings. f In the preferred embodiment of my invention illustrated in the drawings, free air for cooling purposes is forced by blowers 1 through pipes 2 into an air main 3, which is shown in Fig. 4, as forming a art of T e pipe 3 has laterally extending branch pipes 4, one of which enters each cylinder 5 of the waste heater tangentially so as to cause the air to whirl therein and distribute itself about a series of pipes 6 which traverse a chamber, formed between the upper and lower partitions 7 (dotted lines Fig. 4). The tubes establish communication between the chambers at the ends of the cylinders and are arranged closely together as indicated in Fig. 6. The air after passing upwardly through the waste heater-cylinders emerges therefrom near the upper partition through pipes 8, which open into an outlet pipe 9 parallel with the pipe 3 and of equal .diameter. The pipe 9 passes upwardly and discharges into the atmosphere, having absorbed a considerable quantity of heat from the refrigerating medium in the manner which'will now be described.

The refrigerating medium is delivered through pipe 10 and branch pipesll to the upper ends of thewaste heater cylinders and --fiows down through tubes 6 to the bottom of the cylinders from which it passes out through branch pipes 12and the main pipe now describe the apparatus 13, which is shown in dotted lines (Fig. 9.), as leading to the expansion cylinders 14 of the refrigerating machines B, which as illustrated is adapted to be driven by two synchronous motors 15, each of which reciprocates a-piston rod 16 having a piston 17 in the expansion cylinder 14 and a larger piston 18 in the compression cylinder 19, the cylinders 14 and 19 being preferably arranged in tandem, as seen in Figs. 2 and 3. The refrigerating medium under high pressure having been cooled to about atmospheric temperature, is expanded in the cylinders 14 against the pistons 17, exerting power to cotipcrate with the motors in the compressing action taking place in the cylinders 19. A drop in temperature and in pressure in refrigerating medium takes place in the cylinders 14, from which the medium flows through pipe 20 to the condenser (.7, which comprises a series of heat transfer cylinders similar to the cylinders 5, the lower. ends of each cylinder below the bottom partition being connected by branch pipes with the main 20 so that the medium flows up through the tubes in the condenser cylinders and passes out at the top through branch pipes into the main pipe 23 which leads back to the compression cylinders 19 and delivers the medium which has absorbed considerable heat from the dry blast and in this heated condition, to be compressor in the cylinders and its temperature raised still higher. The medium flows from the compression cylinders 19'through the pipe 10 to the top of the cylinders of the wa'steheater A, and in flowing through the tubes in said heaters has its temperature reduced by the cooling blast of air which flows around said tubes in, passing from the pipe 2 to pipe 9.

As thus described, it will be seen that the refrigerating medium, after absorbing heat from the dry blast in the condenser C, is compressed, then cooled in the waste heater A, then expanded in the cylinder 14 and passed through the condenser C, giving it a continuous cycle of travel which permits the use of a gas, such as air, under a high initial pressure to reduce the size of the expansion and compression cylinders relatively to the increase in pressure in the medium. Having thus described the mechanism for directing the refrigerating medium in its cycle of travel through the afpparatus, T will or handling th dry air blast. The blowing engines D deliver the air blast through pipes 25 to an air main 26, which has a valve 27 interposed therein and controls the direct discharge of air from the pipe 26 to a pipe 28 which leads direct to the stoves. This valve is normally closed and the .air blast passes from the pipe 26 to the main air pipe 29, which has a normally open valve 30 therein, and enters the refrigerating apparatus. This transfer E. The blast flows down through the tubes 6 in these'cylinders and passes out at the bottom to a pipe 32 which connects with a waste water pipe 33 leading to a trap 34. The air blast flows upwardly from the heat transfer E through the pipe 32 to the condenser C, being connected thereto by branch pipes which enter the condenser cylinders below the upper diaphragm so that the air flows downwardly around the'condensentubes through which the refrigerating medium, at its lowest temperature, is passing, and has the moisture therein effectively condensed. The air and its entrained moisture flows out of the condenser cylinders through connections leading from above the bottom diaphragms to a pipe 36 which is connected by a pipe 37 to'the water line 33, and which continues to the upper portion of the water separator F, which is constructed on the principle disclosed in Letters Patent No. 1,024,78 i, issued to me on the th day of April, 1912, the air being given a centrifugal whirl in the vortex chamber 39 and having discharged into it electricity by means ofbrush discharges of high tension current from an alternating dynamo and the transformer 40 to cause the particles to be polarized and attract each other, thus forming large drops which are thrown out by centrifugal forceand deflected into'a water chamber 41 from which water is drawn off by a water pipe '42 to the water main 33. The air, thus separated from its condensed moisture, flows out from the water separator through a pipe 43 and is returned to the heat transfer E, being delivered'into the transfer cylinders above the bottom diaphragms so that the dry air flows upwardly with a whirl around the tubes through which the entering blast of wet air is flowing to pipe 32, and thus tends to absorb the heat from said entering wet blast of air, so that when the dry blast leaves the refrigerating apparatus through the pipe'44, it has had transferred to it practically'all of the sensible heat of the entering wet blast and all of this heat is therefore saved. The dry blast flows past the valve 45 vin a pipe 44 and enters the pipe line 28 and flows therethrough to the stoves.

The waste heater A, the transfer E, and the condenser C are shown as comprising each a series of cylinders substantially like the cylinders 5 of Fig. 4, and COIIIPIISIHg each an upper and lower diaphragm connected by a large number of small closely associated tubes, each cylinder having tangentially arranged pipe connections entermg above and below each diaphragm, the ob.

ject of the tangential arrangement being to most efi'ectivelydistribute or collect the air or gas which is in the respective chambers.

For convenience the cylinders are arranged in pairs coupled by short tangential pipe connections to the interposed mains, as seen in Fig. 4, and the several cylinders are supported in suitably braced frame-work 46.

To more .clearl illustrate the operation of my invention, l will give an example of its'use in connection with Fig. 3. Assuming that anhydrous air is the-refrigerating medium used and that it is introduced into the system under an initial compression of 250 lbs., and assuming that the free air flowing through waste heater A has a temperature of the expansion cylinders through Ipipe 13 with a temperature of 95 degrees.

ts pressure having been raised to about 314.7 lbs.,

in the compression cylinders 19, I expand it in the cylinders 14'down to 208 lbs. with a resultant reduction in its temperature to 33 degrees, at which temperature it flows upwardly through the tubes in the condenser C, absorbing heat from the wet blast which enters the condenser at 120 degrees temperature. The compressed air will leave the condenser at 1'15 degrees andlreturn to the compression cylinder. In this cycle of action it is noted that the compressed air is cooled,

-90 degrees, the compressed air will flow to 1 then expanded to a refrigerating temperature, then reheated in refrigerating the wet blast and then compressed, after which it is cooled and the cycle repeated. Assuming that the wet blast enters the heat transfer E at approximately '221 degrees tempera ture and at a compression of 30.7- lbs., it will lose heat in passing through the transfer so that it willleave the same with a temperature of 120 degrees, The drop in temperature is due to the transfer of heat to the dry blast which enters the transfer at a temperature of 38 degrees and leaves at 216 degrees. Meanwhile the wet blast passes to the condenser at the temperature given and passing therethrough has its heat absorbed by the refrigerating medium in the tubes so that it leaves the condenser at a temperature of 38 degrees, at which temperature it passes through the separator and through the transfer absorbing the heat from the enterin wet blast and having its temperature raised to 216 degrees in the manner described. The only heat waste is the loss in the waste heater of the heat units absorbed by the free air blast which is blown through the heater to cool the refrigerating medium before itsexpansion. This free air will discharge from the heater at a temperature of ing and reheating the air, and the apparatus by which said process is carried into effect but no claim is made in this application to condition.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1'. The method of dryingair which consists in compressing the air, cooling it to condense the moisture contained, removing the condensed moisture, and then heating the air by bringing it into heat interchanging relation with the compressed air befor the latter is cooled. I

2. The method of drying air which consists in compressing the air, cooling it to a point. above freezing to condense the moisture contained, removing the condensed moisture, and then heating the airby bringing it into heat interchanging relation with the compressed air before the latter is cooled.- I

3. The method of drying air which consists in first compressing the wet air the required pressure for use, cooling the wet air by bringing it into heat interchangin relation with the air after it has been 0 'lled, lowering the temperature of the cooled air to a point above freezing to condense the moisture therein, removing the condensed moisture" and vapors, and" finally heating dried air by means of the warm wet air in the manner described. v

4. The method of'treatin the air blast of furnaces for the removal 0' moisture which consists in bringing the blast as compressed for furnace use into heat interchan ng relationship .with'the cold com resse an to lower its temperature, then re rigeratin the cooled air to condense its moisture wit out freezing the moisture or lowerin the pressure of, the air blast, then se aratln and removing the condensed moisture cold air, and finally warming said air by heat interchange with the warm compressed all. I

5. The herein described method for extracting moisture from the air blast of furnaees which consists in taking the air blast at furnace gfessure, refrigerating the blast, separating t e moisture therefrom and raising thetemperature of the chilled dry air by causing 1t to absorb heat from the 'wet air before it is refrigerated.

In testimony whereof I afiix my signature in presence of two witnesses.

MARK W. JoH somJR.

Witnessesi Nomm WELSH,

R. D.,Jo'rms1o1-r, Jr.

rom the 

